The complete genome of a bacterium that kills hundreds of thousands worldwide each year has been published by researchers.

The genome of Bordetella pertussis - the complete sequence of all the DNA in the organism - is likely to speed up the search for better vaccines and treatments.

The bacterium causes the infectious disease whooping cough.

Scientists in Cambridge, UK, in collaboration with academics in the US and Germany, have taken years to decipher the DNA and describe the 3,800 genes written in the biological "code".

They also deciphered two other related microbes, B. parpapertussis, which can also cause whooping cough in humans, and B. bronchiseptica, which causes respiratory infections in many animals.

While the full genome has only just been completed, and is announced for the first time in the journal Nature Genetics on Monday, sections of the genetic code completed over the past four years are already benefiting scientists.

Developing world

Professor Duncan Maskell, from the University of Cambridge, and one of those leading the project, told BBC News Online that producing the three genomes had taken an unexpectedly long time.

He said: "In the developing world, there are places where the vaccine is not available.

"Even if you have a vaccine, it is one of those infections which, if you stop vaccinating, comes back straight away.

"Publication of the full sequence will make things far easier for people carrying out research into these bacteria."

Whooping cough is so named because the chest infection it produces leads to a distinctive-sounding cough.

There are an estimated 20 to 40 million cases worldwide every year, and between 200,000 and 400,000 deaths, according to the World Health Organization.

Four out of five children globally are vaccinated against it by the DTP vaccine, including those in the UK.

However, immunity gained this way can disappear in adolescence or adulthood.

The research has already revealed genetic clues about the B. pertussis bacterium, and in particular the damaging toxin it makes.